The embodiments described herein may be useful in inkjet printing and more specifically to systems and methods for printing specific print zones of an envelope.
Certain printers that have print head assemblies, including certain thermal inkjet printers, utilize a shuttle head printing mechanism to enable coverage of the printable area of a page in bands of coverage. For example, a print head carriage may contain one or more print heads having a certain coverage height and width in a single row. Additional cartridges in the row may provide additional colors such as in a CMYK system having a separate head for each color. A single print head may be configured with multiple colors. The carriage may be connected to a guide rail to fix two axes and a positioning mechanism to control movement in an axis perpendicular to a substrate path. The positioning mechanisms that are used include an electric motor connected to an endless belt. Such a printer will paint the entire page by alternatively moving the page and print head over and over in bands of coverage that may include multiple passes in each band. Such a system may allow flexibility in coverage, but may be inherently slow relative to other systems because of oscillating and intermittent head movement. Such a system may paint across the page in one direction only and return the carriage for another pass without printing on the return path. More complicated printing systems may utilize bidirectional printing for increased throughput. Similarly, they may print landscape images using many page and print head movements.
In such shuttle head printers, page movement inaccuracies may cause knit lines (gaps or overlaps) in the printing bands. For inkjet print heads, a shuttle head mechanism may simplify the task of keeping the heads functioning properly by allowing print head xe2x80x9cmaintenancexe2x80x9d by using a portion of the shuttle movement for maintenance tasks including wiping and parking the print head. Certain dedicated envelope printers print envelopes in bands using a shuttle head system.
Certain other printers that have print head assemblies, including certain thermal inkjet printers, utilize a fixed head printing mechanism to enable coverage of the desired print zones. In such a printer, a print head for each zone has been utilized and such printers typically print with pages running lengthwise beneath the print heads. The print heads are typically arranged in staggered mounting assemblies with a mounting assembly for each print zone equivalent to the coverage width of an individual print head. Such a printer may obtain relatively high throughput because there are less oscillating or intermittent movements of the print heads or page. Such fixed head printers utilize unidirectional printing such that all print head characteristics such as drop flight are in the same direction on each printed page. Such a printer would require a large number of print heads and print head mounting assemblies to cover a relatively large portion of a page. In such a system, knit line tolerances are limited to the mechanical tolerances of the print head mounting assemblies. Maintenance may be particularly difficult to accomplish in such print head assemblies as they typically do not move or are moved manually.
In one embodiment, a printer having a bundle of at least two print heads that are configured to provide greater coverage that a single head includes a shuttle mechanism for passing the bundled heads over a stopped substrate to cover print zones on the substrate in a single pass. In another embodiment, a method of printing two consecutive substrates involves moving the bundle from a maintenance position across the first substrate to print the print zones in one pass in that direction until reaching an end position, and when the second substrate is in place, returning across the path to print the print zones of the second substrate in the second direction in one pass. In another embodiment, the bundle returns to the maintenance station position while the maintenance station moves a wiper across the heads and then positions a cap to cap the heads of the bundle.